The one that gets
welded into things.
High-Density Polyethylene is the workhorse. It is stiffer and stronger in tension than UHMW, it costs meaningfully less, it is FDA and NSF compliant, and unlike most plastics it welds — which is why every fabricated tank, launder, liner, and containment weldment that leaves our shop starts as HDPE or polypropylene sheet.
Stock & Sizes
We stock HDPE sheet in white, black, and natural (translucent), in the thicknesses below, cut to size same day. Colored and textured HDPE can be brought in for specialty work — playground panels, marine board, and two-tone engraving stock. The gauges are drawn edge-on beside each size, all at the same scale, so you can see the difference rather than work it out. Thicker resists deflection and lasts longer in wear; thinner costs less and forms more easily.
What’s on the rack in Sparks
| Thickness | Decimal | Edge on, to scale | Cut to size |
|---|---|---|---|
| 1/8″ | 0.125″ | Same day | |
| 3/16″ | 0.1875″ | Same day | |
| 1/4″ | 0.250″ | Same day | |
| 3/8″ | 0.375″ | Same day | |
| 1/2″ | 0.500″ | Same day | |
| 3/4″ | 0.750″ | Same day | |
| 1″ | 1.000″ | Same day |
Seven thicknesses on the floor, cut to your dimensions the same day — one piece or a full sheet. Above 1″ we source to order, up to 4″. Tell us the thickness and we will confirm whether it is a same-day cut or a short lead time before you plan around it.
If you are running a repeat part — a cutting board size, a liner profile, a dock component — tell us and we will keep the pattern on file so reorders are a phone call rather than a fresh quote.
Typical Properties
| Property | Typical value | What it means on the job |
|---|---|---|
| Density | 0.95–0.96 g/cm³ | Light, floats, easy to handle in large panels |
| Tensile strength | 4,000–4,600 psi | Stronger in tension than UHMW — better for structure and pressure |
| Elongation at break | 600–800% | Very ductile. Bends and yields rather than snapping |
| Coefficient of friction | 0.20–0.29 (dynamic, on steel) | Slick, but noticeably higher than UHMW — not a sliding-wear material |
| Service temperature | −50°F to +180°F | Fine for wash-down and outdoor service; not for hot process |
| Water absorption | < 0.01% | Dimensionally stable wet. Will not swell, rot, or delaminate |
| Chemical resistance | Excellent | Most acids, bases, salts, and alcohols at ambient temperature |
| Weldability | Hot-gas / extrusion | Fabricates into leak-tight tanks and weldments |
| FDA / NSF | Compliant (natural & white) | Direct food contact and commercial kitchen work |
| UV stability | Good in black; specify UV grade in colors | Black is the default for permanent outdoor installs |
Typical published values for HDPE sheet, given as a design starting point. For containment, structural, or regulated work, ask and we will supply the mill certification for the specific sheet.
Where It Wins, on Charts
HDPE carries more load in tension than UHMW, costs less per square foot, and unlike UHMW it welds. Those three facts together are why every fabricated tank, launder, and containment weldment that leaves our shop starts as HDPE or polypropylene. Full UHMW vs. HDPE comparison →
About an eighth the weight of steel, and it floats. On dock boards, marine components, and large containment panels that is not a spec detail — it decides how the thing gets handled and installed.
HDPE moves about fourteen times as much as steel, and UHMW about seventeen — more than anything else we stock. On any large or fastened panel, use oversized or slotted holes and leave clearance at every edge. Skipping this is the most common reason a panel bows or tears out a fastener a year after it went in.
Where It Gets Used
HDPE or UHMW?
Short version: HDPE if the part holds something or gets welded; UHMW if the part slides or takes abrasive wear. HDPE is stronger in tension, welds into leak-tight assemblies, and costs less. UHMW wears roughly 6 to 10 times longer and runs at about half the friction. Picking on price alone is how a chute liner gets replaced three times in a year. Full side-by-side comparison with the numbers →
Fabrication
HDPE machines, routes, and bends predictably, and it is one of the few plastics that welds into a genuinely leak-tight assembly. We cut to size, CNC rout, and plastic weld it in our Sparks shop — tanks, launders, containment, and weldments fabricated to drawing. Note that HDPE will not solvent-cement or take paint; joints get welded and graphics get engraved or applied.
Common Questions
Can you build me a tank out of it?
Yes — that is a large part of what our welding shop does. Process tanks, launders, containment, and drip pans in HDPE and polypropylene, fabricated to your drawing in Sparks rather than freighted in from out of state with the lead time to match.
Is HDPE food safe?
Natural and white HDPE is FDA and NSF compliant for direct food contact. It is the standard material for commercial cutting boards. Colored and reprocessed grades generally are not certified — if it is going in a kitchen or a food plant, say so and we will pull the right sheet.
Why won't glue stick to it?
Same reason it resists chemicals: polyethylene has a very low surface energy and almost nothing bonds to it. Do not plan on adhesive. Parts get welded or mechanically fastened, and that is a design decision worth making early rather than discovering at assembly.
Will it hold up outdoors?
Black HDPE is UV-stable and lasts for years outside — docks, agricultural panels, playground components. Natural and white will chalk over time in sustained sun. Specify black or a UV grade for permanent outdoor installs.
How hot can it run?
Up to roughly 180°F. It softens above that and will creep under sustained load, so it is not a hot-process material. If your service temperature is higher, tell us — polypropylene or a different family may be the right answer and we would rather redirect you than sell you the wrong sheet.
How much does it move with temperature?
A lot — HDPE expands about fourteen times as much as steel (UHMW about seventeen). On anything large, fastened, or fitted between structure, build in clearance and use slotted holes. This is the most common cause of a panel bowing or a fastener tearing out a year later.
One hour. Tomorrow. Or today when it can’t wait.
We stock it here and we run our own van. Three ways to get material — take the one you need.
